How fickle sport is. Barely a handful of months ago, all roads seemed to lead to Naomi Ozaka if you were discussing women's tennis.
In January she claimed her fourth Grand Slam title by winning the Australian Open in Melbourne where she dropped just a single set over seven matches.
For the first time since Serena Williams vacated the role of top female player on the planet, there appeared to be a genuine replacement.
Yet, in May, the 23-year-old from Japan stunned the tennis world by withdrawing from the French Open after winning her first round match.
Ozaka, who did not wish to speak to the media, cited mental health issues, and subsequently pulled out of Wimbledon too.
She was one of many sport stars to recently speak out about the psychological pressures of being constantly in the media spotlight.
She returned to action at the Olympic Games in Tokyo, but just days after being given the honour of lighting the flame in her home country, suffered a shock third round defeat in the women's singles.
Ozaka lost in straight sets (6-1 6-4) to world No 42 Marketa Vondrousova who went on to secure the silver medal.
From there it was on to Cincinnati for the Western & Southern Open where she beat Cori Gauff in her opening match, before losing to Switzerland's world No 76 Jil Teichmann.
Compared to this time last year, when Ozaka headed to the US Open as the favourite - and then won the tournament - there appears to be much greater uncertainty over her current form.
More losses than victories
That said, she'll be on her favourite surface as a two-time champion in New York, but having lost five of her last nine competitive matches, her reputation as the new big star of the women's game has taken a massive hit in recent months.
Latest odds for the women's singles in New York
Seemingly flying high right now is world No 1 Ashleigh Barty, who won the Wimbledon title in July.
The 25-year-old Australian missed 11 months of tennis, after deciding not to compete during the height of the Covid-19 pandemic, but returned to the WTA Tour earlier this year and has since won five tournaments.
She held her nerve at crucial moments to claim a second Slam trophy at SW19 and, although suffering a surprising first round loss in Tokyo, bounced back to lift the title in Cincinnati without dropping a single set.
Two of the home country's top-three ranked players, Serena Williams and Sofia Kenin, have withdrawn from the tournament. Kenin tested positive for Covid, while Williams has a hamstring injury.
As for others in the spotlight at Flushing Meadows
Belinda Bencic: Stunned the tennis world, and perhaps herself too, by claiming gold in Japan. It was her first title in two years but will have given the world No 12 plenty of confidence heading into the US Open.
Cori Gauff: The teenager will be a handful playing on home soil but probably still lacks that consistency to go all the way in the Big Apple. Yet capable of beating anyone she faces. America's best singles hope in this tournament.
Angelique Kerber: Appears to have rediscovered her mojo. The three-time Slam winner, now 33, reached the semi-finals at both Wimbledon and Cincinnati, and on each occasion lost to Barty.
Latest odds for the men's singles in New York
Karolina Pliskova: The Wimbledon runner-up whose favourite surface is hard court. The tall 29-year-old from the Czech Republic is back up to No 4 in the world and should be a regular challenger for big titles. Was a semi-finalist in Cincinnati, while losing in the final at Montreal a week earlier. US Open runner-up five years ago.
Aryna Sabalenka: The 23-year-old from Belarus has long been tipped as a future Slam winner but so far has only reached the last eight once. On that occasion at Wimbledon, earlier this summer, she made it to the semi-finals where she lost to Pliskova in three sets.
Iga Swiatek: Has settled into life as a top 10 player, following her stunning victory at the French Open last year. The 20-year-old from Poland has added two more titles during 2021.
Click here to view 10-year form at Flushing Meadows
Twitter: Andy Swales@GolfStatsAlive